Bobbin brake



Feb. 1 1943. 1. v. Hl'l 'T 2,311,175

BOBBIN BRAKE Filed Jul 14 1941 JTgQE.

ATTDRNEY INVENTOR.

. Patented Feb. 16, 1943 BOBBIN BRAKE Ira V. Hitt, Kenmore, Va assignorto E. I. 'du' Pont de Nemours & Company, Wilmington, DeL, a corporationof Delaware Application July 14, 1941, Serial No. 402,351

3 Claims.

This invention relates to the winding of textile yarns and moreparticularly the means for stopping the rotation of the yarn packagewhen it is moved from its-operating position.

In a widely employed method of winding yarn,

package or at any other time when dofling of the core or yarn package isdesired.

The invention will be further described in con nection with theaccompanying drawing wherethe yarn package, mounted on a swing arm, is

surface driven by frictional contact with a drive roll rotated atconstant angular velocity. This method of winding is especiallydesirable in the winding of freshly for-med bundles of artificialfilaments, for instance, a bundle of cellulose acetate filaments formedby the dry or evaporative spinning process, since in this way constantdrawofi from the spinning cell is easily maintained and thereforeuniform denier of the yarn. When the package is completed, i. e., whenthe core or bobbin is completely filled, it is doffed by merely swingingit away from the drive roll through an arc of 90 or more to a fixeddotting position, removing the full package of yarn and inserting anempty core before returning it to its operating position.

In the winding of relatively small packages of yarn, it has beencustomary for the operator to retard rotation of the package afterbreaking contact with the drive roll by merely press- I ing the end ofthe core holder with his hand. The rotational inertia is relativelysmall and rotation of the package can be brought to a stop within asecond. However, with the art tending toward larger and larger packagesnecessitating in some cases heavier core assemblies in addition to theincreased yarn weight, the rotational inertia of the winding assemblybecomes several times greater. Not only does it take longer to stop therotation of the takeup yarn package, but in view of the greater mass,

Fig. 1 is an end section of a winding assembly on the line le| of Fig. 2and shows a preferred embodiment of the invention in the winding ornon-braking position;

Fig. 2 is a front-elevation of the winding assembly with parts outaway'on the line 2-2 of Fig. 1 to show the brake mechanism;

Fig. 3 is an end section showing the brake in operative position; and

Fig. 4 is an end section showing a modified 4 which is fixed to swingarm 5. Swing arm 5 is pivoted at its lower end (not shown) and the oldpractice of hand braking becomes un- This object is accomplished bymeans of a gravity actuated braking shoe pivotally mounted inside thewinding assembLv so as not to interiere with the rotation of the windingassembly during the winding period, but which automatically becomesoperative to retard the rotational speed of the winding assembly as soonas the package is brought into its dofling posi tion on completion ofthe winding of ayarn serves to shift or swing the bobbin assembly firstinto winding position wherein the bobbin assembly is driven by apositively driven surface drive roll 6, and then into doffing position(Fig. 3) after the yarn package is completed. This winding assembly isessentially the same in construction and operation as that disclosed inU. S. Patent No. 2,150,951. Pivoted to swing arm 5 is a brakecomprisinga main body portion I and a brake shoe 8. of the brake shoe isshaped to conform with the adjacent inner surface of hub 2. The mass ofthe brake isso distributed that the shift in the center of gravity ofthe mass occasioned by movement of shift arm 5, will cause the brake tooperate as hereinafter explained.

' In the modified construction shown in Fig. 4,

remains pressed against the stationary'spindle as shown (Figs. 1, '2,and 4) during the entire winding period but, When the assembly is liftedaway from the drive roll and swung into the dofl'lng position (Fig. 3),the center of gravity of the brake is moved to the other side of thepivot point and the brake swings by'its own weight The outer surfaceagainst the inner rotating surface of the hub portion of the bobbinassembly and almost instantaneously stops the motion of the package. Itis thus possible to wind a package of three or four pounds of yarn and,when the package is completed, stop rotation of the windup assemblyautomatically within a second from the time it is lifted from the driveroll.

It will be understood, of course, that the invention is not restrictedto the exact structure described above and shown in the drawing, but

is obviously susceptible to thenumerous modifications and variationswithin the skill of the mechanic. Accordingly the invention comprehendsall of such modifications and variations falling within the terms andspirit thereof as set out in the following claims. I

I claim:

1. In a thread winding mechanism wherein a hollow bobbin assembly,freely rotatable on a fixed spindle, is driven by a positively drivensurface drive roll, and wherein the bobbin filled with thread ismovableout of contact with said roll for domng, the improvement whichcomprises a brake element within said hollow bobbin assembly saidelement being swingably mounted on a pivot and being so proportionedthat when said bobbin assembly is in a winding position the center ofgravity of said element is to'one side of a vertical line passingthrough said pivot whereby said element is gravity actuated free of saidbobbin assembly, and when said bobbin assembly is in dofiing position,the center of gravity of said element is to the opposite side of saidvertical line whereby said element is gravity actuated into brakingcontact with said bobbin assembly.

2. In a thread winding assembly comprising a horizontally disposed,positively driven surface drive roll, a bobbin assembly freely rotatableon a spindle fixed to a pivoted arm said arm being operable to positionsaid bobbin assembly in and out of driving relationship with the driveroll, the improvement which comprises a brake element provided with abrake shoe shaped to conform with an inner surface of said bobbinassembly said brake element being pivotally mounted on said arm andhaving its mass so distributed with respect to its pivot point that whenthe bobbin assembly is in driving relationship with the drive roll, thecenter of gravity of said brake element is to one side of a verticalline passing through its pivot whereby said brake shoe is gravityactuated free 'of the bobbin assembly, and when the bobbin assembly isout of driving relationship with the drive roll, the center of gravityof said brake element is to the opposite side of said vertical linewhereby the brake elements is gravity actuated to a position where thebrake shoe frictionally engages the inner surface of the bobbin assemblywhereby to prevent the free rotation of the bobbin assembly.

3. A thread winding device comprising an arm mounted for limitedmovement in a vertical plane and about a. pivot at one end thereof, aspindle fixed substantially normal to, and at the opposite end of, saidarm, a hollow cylindrical bobbin assembly freely rotatable on saidspindle, and a brake element pivotally mounted on said arm to swingwithin said hollow bobbin assembly, said brake element being soproportioned that its center of gravity is to one side of a verticalline passing through its pivot whereby said brake element is gravityoperated to swing into braking contact with the inner wall of saidbobbin assembly at one limit of motion of said: arm whereby to preventrotation of said bobbin assembly.

. IRA V. HITT.

